EP3601955B1 - Interference field-compensated angle sensor device and method for interference field-compensated angle determination - Google Patents

Description

The invention relates to an interference field-compensated angle sensor device and an interference field compensation method based on a magnetic field-based determination of an angle of rotation of an axis of rotation. A magnetic field generating device generates a magnetic field which rotates relative to an angle sensor device, the angle sensor device being able to determine the angular orientation of the rotating magnetic field.

STATE OF THE ART

A large number of magnetic field-based angle sensor devices are known from the prior art, which can determine the angle of rotation of an axis of rotation without contact on the basis of magnetoresistive resistance elements. Among other things, such sensors are used in the automotive sector and in the field of electrical machines, for example to determine an angle of rotation or a frequency of rotation of a rotating motor or drive shaft, a wheel shaft or a steering wheel angle.

In the technical environment, the number of electromagnetic interference sources that cause electrical or magnetic interference fields is constantly increasing. This is also known as electrosmog. Electromagnetic sensors that use the measurement of an electrical or magnetic useful field must be able to be tolerant of these interference fields and, to a certain extent, perform a measurement correctly under the influence of an interference field. Particularly in the automotive sector, the ISO-11452-8: 2015 "Road vehicle component test method for electrical disturbance variables through narrow-band radiated electromagnetic energy - Part 8: Immunity to magnetic fields" requires that electromagnetic sensors based on the detection of a useful magnetic field, disturbance fields in the area of 1 kA / m up to 3 kA / m field strength and must tolerate exact Should show values.

Thus, in recent times, attempts have been made to develop interference field compensation measures which attempt to compensate for magnetic interference fields in angle measurement sensors.

For example by Thomas Tille: "Automotive sensors, selected sensor principles and their automotive application", BMW AG, Springer Vieweg Verlag, 2016, ISBN 978-3-662-48943-7 on pages 242 to 250 a magnetic angle sensor system integrated in a shaft is presented, in which an angle sensor is shielded by a ferromagnetic hollow cylinder wall of the shaft in order to be able to compensate for interference fields. Electromagnetic shielding of this type for the angle sensor requires a great deal of construction effort and can only be used in a practical manner in a few applications.

In addition, for example, from the WO 1998/054547 A1 a Hall-based angle measuring sensor is known in which four Hall resistors are arranged in a bridge circuit, each resistor being able to measure a vector component of a rotating magnetic field and the four resistors of the measuring bridge being arranged axially distributed around an axis of rotation in order to compensate for the effect of an interfering magnetic field to be able to. Thus, a single angle sensor is enlarged radially in order to be able to compensate for an almost homogeneous interfering magnetic field through the opposing orientations of the individual resistance elements of the measuring bridge. For this purpose, a relatively large chip area is required or an enlargement of the sensor device is required, which in many cases is not practical.

Furthermore, the US 8,659,289 B2 a magnetic field-based angle measurement sensor device comprising two angle measurement sensors, each angle measurement sensor being assigned to a magnetic field generating device, that is to say a permanent magnet, and measuring a rotating magnetic field provided by the permanent magnet. The magnetic fields that act on the both angle measuring sensor devices act are independent of one another. The relative position of the angle measuring sensor devices with respect to the magnetic field generating device is identical, only the orientation of the useful magnetic field is changed in order to be able to compensate for such influences of an interference field. The two angles output by the two angle measuring sensor devices are offset against one another in accordance with the relative position of the useful magnetic fields and the angle measuring devices to one another. Since the angle measuring devices are exposed to different magnetic fields from different permanent magnets or see different magnetic fluxes from a magnetic field generating device, compensation can be achieved based on a coordinated provision of the different magnetic fields and an identical behavior of the angle measuring sensor devices. For this purpose, a relatively expensive and exact manufacture of the angle measuring sensor device is necessary, which results in a correspondingly costly method and a correspondingly expensive sensor.

The DE 10 2016 202 378 A1 relates to an angle sensor device, whereby in the sense of the invention an overall system with angle sensor device (electrical part) and magnetic field generating device with rotating magnets (mechanical part) with an angle measurement sensor device (only electrical part) is meant, and the angle measurement sensor device means an angle sensor with two angled groups of sensitive elements includes, which are designed to output an angle signal. The angle sensor comprises a first group of sensitive elements and a second group of sensitive elements. The first group is designed to detect a magnetic field along a first direction, the second group is designed to detect the magnetic field along a second direction, preferably 90 ° to the first direction. An evaluation unit determines an angle signal from the signals of the sensitive elements of the first and second group. Thus, an angle sensor is proposed in which a sine and a cosine signal are each measured with three magnetoresistive elements and can be determined into a single angle signal. In further developments, it is proposed to determine the sine and cosine signals redundantly by measuring two of the three sensitive elements, and thus to average two or more sine and cosine values. In each case, however, only a single angle value is determined, so that within the meaning of the invention it is only possible to speak of a single angle sensor that outputs only a single gradient.

The DE 10 2014 109 693 A1 relates to a generic angle sensor device with a rotating multi-pole permanent magnet, and an angle measuring sensor device, which comprises an angle sensor with at least Hall elements, which are arranged along a circular path, and whose signals are calculated to determine an angular position by means of illustrated trigonometric relationships. In one variant, it is proposed to provide three further Hall elements of a second angle sensor, which are arranged along the circular path offset with respect to the first Hall elements. Differences in the angle determination by the two angle sensors can minimize an interference field. In the DE 10 2014 109 693 A1 the use of second angle sensors for interference field compensation can thus be recognized. However, the Hall elements of the two angle sensors are angled offset from one another on a common circular path, with no axial or radial displacement of the angle sensors relative to the axis of rotation being discernible. In this case, no gradient of angle values of the two angle sensors is determined, but rather interference fields are calculated by determining the gradients of individual sensor element values by means of complicated trigonometric relationships.

From the DE 10 2010 040 584 A1 also shows an angle sensor device with an angle sensor unit which comprises an angle sensor which comprises two sensor elements. These are arranged in a circular path around a rotating magnet and provide a sine and cosine signal. The DE 10 2010 040 584 A1 recommends the effect of an interference field, for example To determine commissioning and, for example, in the form of characteristics or calculation rules to be deducted from the sensor signals when determining the angle value. In this respect, the DE 10 2010 040 584 A1 only one angle sensor and tries to actively compensate for static or dynamic external field influences in test or simulation scenarios in advance, for which a corresponding evaluation logic or computer capacity must be provided. The DE 10 2010 040 584 A1 does not react to unexpected external field influences and also does not have two angle sensors for the independent determination of two angle values. Also, no radial or axial displacement of such angle sensors with respect to the axis of rotation can be detected.

Furthermore, the DE 10 2013 205 313 A1 an angle sensor device with an angle sensor device which comprises an angle sensor consisting of at least three diagonally opposite pairs of Hall sensors arranged in a circle. The resulting three or more measurement signals from the Hall sensor pairs are calculated to form a common angle signal. In this respect, the concept of DE 10 2013 205 313 A1 Similarities with the concept of DE 10 2016 202 378 A1 and DE 10 2014 109 693 A1 because a redundant number of sensors is provided in an angle sensor in order to eliminate interference fields. However, are also in the DE 10 2013 205 313 A1 As in the other publications, no explicitly separate angle sensors are specified for the independent detection of two angle values, and there is also no discernible axial or radial displacement of the angle sensors or the sensor elements based on them.

The DE 10 2011 083249 A1 discloses several angle sensor devices with a magnetic field generating device and an angle sensor device which comprise two angle sensors. A magnetic field of the magnetic field generating device rotates relative to the angle sensor device, with different magnetic field areas of the magnetic field of the magnetic field generating device being detected in these devices. A first angle sensor is located at a first position and a second angle sensor 20 is located at a second position, the reference directions of the first angle sensor and the second angle sensor differing. Both angle sensors are at the same distance from the magnetic field generating device and measure identical amplitudes of the useful magnetic field.

From the DE 10 2011 080679 A1 shows an angle sensor device with two magnetic field generating devices, two magnetic field sensors being arranged in oppositely oriented magnetic field areas of separate useful fields of the two magnetic field generating devices. In addition, this document also shows an angle sensor device with a magnetic field generating device, the two angle sensors being arranged in areas of opposite magnetic field orientations.

Finally concerns the DE 101 30 988 A1 an adjustable angle sensor device with one of two magnetoresistive measuring bridges aligned at an angle to one another. A correction factor for the measuring bridge signals increases the accuracy of the angle sensor.

Based on the above prior art, it is the object of the invention to propose an angle measuring sensor device which is inexpensive and simple to manufacture and which enables an effective compensation of an interference field without great structural effort.

This object is achieved by an angle measurement sensor device and an angle measurement sensor method according to the independent claims.

Advantageous embodiments of the invention are the subject of the subclaims.

What is essential for the invention is the fact that the angle sensors are arranged axially at different distances along the axis of rotation and / or the angle sensors are arranged radially at different distances from the axis of rotation.

Therefore, only the arrangements of the Fig. 6-11 under the subject matter of claim 1 and the following description is also to be interpreted in this way.

DISCLOSURE OF THE INVENTION

According to the invention, an interference field-compensated angle sensor device for magnetic field-based determination of an angle of rotation of a rotation axis is proposed, which comprises at least one magnetic field generating device, in particular a permanent magnet, and an angle sensor device, a magnetic field (useful magnetic field) of the magnetic field generating device rotating relative to the angle sensor device. This means that either the permanent magnet is at rest and the angle sensor device rotates with the axis of rotation, or the magnetic field generating device rotates with the axis of rotation and the angle sensor device is at rest.

The invention proposes that the angle sensor device comprises at least two angle sensors which are arranged axially and / or radially offset to the axis of rotation so that an influence of an interference field can be compensated for by an algebraic evaluation of the angle values or the sensor signals of the at least two angle sensors.

In other words, the angle sensor device comprises at least two angle sensor devices, each of the angle sensor devices being set up to detect the angle of a magnetic field, to output sensor signals, in particular a sine and a cosine value, which result in an angle value of the useful magnetic field through an arctangent operation. The at least two angle sensors of the angle sensor device are arranged axially offset from one another and / or are arranged offset radially to the axis of rotation. Accordingly, the two angle sensors detect different magnetic field areas of a single useful magnetic field of the magnetic field generating device. This makes it possible, for example in the case of an axial offset, to detect different amplitude values of the useful magnetic field of the magnetic field generating device, or in the case of With a radial offset, it may be possible to detect different phase values of the useful magnetic field of the magnetic field generating device, in particular if the two angle sensors are arranged offset in a circle around the circumference of the axis of rotation, or detect different values of the magnetic field of the magnetic field generating device in terms of amplitude. An externally generated interference field has the same effect on both angle sensors since the two angle sensors are closely adjacent in relation to the interference field source. This can result in a gradient, ie a difference in the angle detection or the sensor signals of the two angle sensors. Thus, when comparing an undisturbed angle sensor device and a disturbed angle sensor device and the resulting different gradients of the output angles or the sensor signals of the two angle sensors, the size and possibly also the direction of the interference field can be determined, with the influence of the interference field being compensated arithmetically or by the hardware. can be minimized or eliminated. The gradient can be determined through hardware wiring or determined through software processing.

To this extent, the invention is based on the idea of detecting different influences of the useful magnetic field of the magnetic field generating device by means of a radially or axially offset arrangement of angle sensors of the angle sensor device, and with almost the same influence of an interference magnetic field and the known differences in angle detection due to the offset, the size of the interference field can determined and / or its influence compensated. In practical implementation, the influence of the interference field can be reduced or compensated for, at least without knowledge of the size and direction of the interference field.

In this respect, the interference field-compensated angle sensor device according to the invention for the magnetic field-based determination of an angle of rotation of a rotation axis comprises a magnetic field generating device (Permanent magnets) and an angle sensor device, wherein a magnetic field of the magnetic field generating device rotates relative to the angle sensor device. It is essential to the invention that the angle sensor device comprises at least two separate angle sensors which are arranged axially and / or radially offset to the axis of rotation and which can output two independent angle values so that an influence of an interference field can be compensated for by determining the gradient of the angle values of the angle sensors.

In an advantageous development of the invention, the magnetic field generating device can be designed as a permanent magnet, in particular a dipole magnet with two pronounced magnetic poles, preferably as a disk-shaped dipole magnet with a circular disk half as the north pole and a circular disk half as the south pole, which is arranged in a rotationally fixed manner on an end face of the axis of rotation, the angle sensor device is arranged in an axial extension of the axis of rotation opposite to the end face of the axis of rotation. It is hereby proposed that a permanent magnet be arranged in a rotationally fixed manner with the axis of rotation, which in particular comprises a dipole magnet with two distinct magnetic poles. The two magnetic poles are arranged in such a way that they form a gradient field in the direction of the axis of rotation, in particular as a disk-shaped magnet with half a circular disk that is magnetized as the north pole and half a circular disk that is magnetized as the south pole. This forms a U-shaped or club-shaped magnetic field in both directions of the permanent magnet, in which angle sensors of the angle sensor device can be arranged in a sensitive measuring plane perpendicular to the axis of rotation or parallel to the axis of rotation in order to be able to measure an angular position of the useful magnetic field of the magnetic field generating device. The angle sensor device can in principle either be arranged as an extension of the axis of rotation or set back along the axis of rotation, a radial offset of the angle sensor device being particularly advantageous, especially if only a small amount of installation space is available stands. If the angle sensor device is arranged as an extension of the axis of rotation, the angle sensors can be arranged both along the axis of rotation and also radially offset; a high level of accuracy can be achieved in the positioning of the angle sensor device, so that a high level of accuracy in angle detection can be achieved.

In an advantageous development, the angle sensors are based on an xMR sensor topology, in particular an AMR, TMR or GMR magnetoresistive sensor topology. The sensor types known as xMR angle sensors are distinguished from Hall sensors by up to 50 times higher sensitivity, so that they enable highly accurate angle determinations, especially in weak field operation with field strengths <1kA / m. MR sensors can detect the earth's magnetic field for compass applications and are successfully used for non-destructive material testing and vehicle detection. In these applications, extremely weak magnetic fields are measured very precisely. Furthermore, xMR angle sensors typically have a higher accuracy of up to 0.1 ° without the sensor signals having to be post-processed in a complex manner. At the same time, this leads to a higher bandwidth since no signal conditioning processes such as the spinning current principle are required to achieve a high angle accuracy, significantly better than 1 °. This type of sensor is based partly on thin-film effects and partly on magnetoresistive properties of a premagnetized layer, the current flow being angled to the internal magnetization in order to enable a highly accurate resolution of the magnetic field direction.

In an advantageous development, each angle sensor can comprise a Wheatstone measuring bridge made of magnetoresistive resistance elements, the Wheatstone measuring bridges of the various angle sensors being hard-wired and outputting an interfering field-compensated angle sensor value. Each angle sensor usually includes two Wheatstone measuring bridges that determine a sine and a cosine component of a magnetic field can, and which in the case of GMR and TMR sensors are generally offset by 90 ° and in the case of AMR sensors generally offset by 45 ° on a chip substrate. The angle sensor device comprises at least two or more angle sensors which, due to a different spatial arrangement in the useful magnetic field of the magnetic field generating device, have different sensitivities for an interfering magnetic field. Furthermore, due to the spatial position, a phase offset or an amplitude offset of the useful magnetic field can also occur. By interconnecting the individual measuring bridges of the various angle sensors in the correct phase, an interfering field-compensated angle can be determined in that the influence of the interfering magnetic field can be compensated for by the different localization of the angle sensors. Thus, the angle sensor device outputs a compensated angle and there is no need to subsequently process different angles in order to be able to calculate the influence of an interfering magnetic field.

For example, two or more angle sensors can be arranged in a circumferential circle around the axis of rotation and offset from one another by predetermined angles, for example 90 ° or 180 °. Thus, a bridge resistance of an angle sensor that detects a sine component can be hard-wired with a cosine measuring bridge of a 90 ° offset or wired phase-reversed with a sine measuring bridge offset by 180 ° of an angle sensor offset by 180 °. Both angle sensors are subject to the same influence of an interfering magnetic field, whereby the influence of the interfering magnetic field can be compensated for by interconnecting the various resistance bridges in the correct phase.

In an advantageous development, an angle calculation device can be included which receives angle values or sensor signals from each angle sensor of the angle sensor device and processes them to calculate an interference field-compensated angle value. So it is conceivable that two or more angle sensors of the angle sensor device have their angle value to the angle calculation device, and these angle values are offset against one another in an angle calculation device, for example, taking into account an arithmetic function, tabulated values, characteristic diagrams or the like for interference field compensation. The gradient, ie the deviation of the angle values or sensor signal values of the individual angle sensor devices, can be recorded, for example, in a calibration or measurement method for an interfering field-free and an interfering field-affected angle measurement in order to be able to calculate the size and direction of an interfering field. For example, the size and direction of the interference field can be determined with a corresponding table or a characteristic diagram. In practice, compensation can also be achieved by weighting with a single factor, by means of which an angle value that is almost free of interference fields is generated from the two sensor signals. It is not absolutely necessary to determine the size and direction of the interference field.

In an advantageous development, at least two or more of the angle sensors included in the angle sensor device are arranged axially centered. Due to an axis-centric arrangement, the angle sensors detect the same angular value of the useful magnetic field in superposition with the interference field, but the influence of the useful magnetic field is reduced with increasing distance along the axis. As a result, an interference field has a stronger effect on the more distant angle sensors than on the closer angle sensors, which results in different measurement angles. This results in a deviation of the angle values, the angle value of the angle sensor located closer to the magnetic field generating device being closer to the useful field angle than the angle value of the remote angle sensor. This influence can be significantly compensated for by the gradient of the angular deviation or the sensor signals between the angle sensors and their distances from the magnetic field generating device. In practice, full compensation can only be achieved with great effort, but there is a significant reduction in the interference field influence relatively easy to reach.

In a further development of the aforementioned embodiment, each angle sensor of a Wheatstone measuring bridge can advantageously comprise magnetoresistive resistance elements, the radial distances between the magnetoresistive resistance elements of the Wheatstone measuring bridge of each angle sensor being different from the axis of rotation. For example, each individual angle sensor can include not only resistors for two measuring bridges but for four or more measuring bridges, the individual resistors, for example for the sine and cosine measuring bridges, being arranged axially centered, but having different radii to the axis of rotation. In this case, depending on the structure of the useful magnetic field, the resistors arranged further away from the axis of rotation have a stronger or weaker influence of the useful magnetic field. The resistors of the bridge circuits can be wired to one another in such a way that the influence of an interfering magnetic field, which has the same effect on all resistors of the angle sensor, can be compensated. In particular in the case of an axially arranged angle sensor, two or more resistance elements arranged along a circle or rectangle around the axis can take into account the influence of an interfering magnetic field by creating a gradient, whereby the individual resistors can be hard-wired in the Wheatstone measuring bridge.

In an advantageous development of the previous exemplary embodiment, radially offset magnetoresistive resistance elements of the angle sensors can be connected in opposite directions to form a compensating Wheatstone measuring bridge. For example, it is conceivable to arrange an angle sensor axially centered and to arrange resistance elements for the sine and cosine bridges along a circumferential circle or a circumferential rectangle, with two or more radial circumferential circles or circumferential rectangles being provided. Associated magnetoresistive resistance elements of two or more measuring bridges are thus in a radial one Relocation can be arranged. Radially offset resistance elements can be connected in opposite directions in a measuring bridge. A useful magnetic field has different effects on the radially offset resistance elements, while an interfering magnetic field has the same effect. Due to the opposing connection of the resistance elements in the measuring bridge, the influence of the interfering magnetic field, which has the same effect on all resistance elements, can be compensated. This provides an effective and structurally simple measure for compensating for an interfering magnetic field, it being possible to provide a chip with a correspondingly large area. The influence of the useful magnetic field on a group of resistance elements, which are arranged along one of the closed circumferential circles or circumferential rectangles, has a particularly strong effect compared to another group which is radially offset. It is nevertheless conceivable that the two groups are offset radially and axially with respect to one another.

In an advantageous development, a radial position of the angle sensors can be different, in particular at least two angle sensors can be arranged radially opposite one another, or preferably four angle sensors can be arranged on a circular path offset by 90 ° around the axis of rotation. As a result, radially spaced angle sensors of predefined offset angles, in particular 90 ° or 180 °, are proposed, which are included in the angle sensor device. The angle sensors measure the useful magnetic field in a specified phase position; for this purpose, their sensitive measuring surface is aligned parallel to the axis of rotation and can, for example, measure a rotating field of the useful magnetic field with a 90 ° offset in 90 ° phases. An interfering magnetic field would have the same influence on all angle sensors and can be compensated for if the angle values of the individual angle sensors are combined in the correct phase. There is the option of permanently wiring the individual measuring bridges of the angle sensors, so that a common angle value can be created, for example, by creating an ArcTangent without complex calculation unit can be output. Alternatively or additionally, the individual angle values of the individual angle sensors can be connected to one another in a calculation unit in order to be able to computationally compensate for the influence of the interfering magnetic field.

In an advantageous development of the previous exemplary embodiment, the magnetic field generating device can comprise a permanent magnet with the same number of poles as angle sensors, in particular a quadrupole magnet. In relation to the previous embodiment, it is proposed to use an embodiment of an angle sensor device with four angle sensors offset by 90 ° and a quadrupole magnet as a magnetic field generating device, the quadrupole magnet each having circular segments offset by 90 ° with alternating polarity. In this embodiment, the angle sensor device can detect 90 ° or 180 ° rotations depending on the resistance technology used, with all angle sensors ideally displaying rigidly phase-shifted values and, if there is a phase difference, the sensors arranged along a Y-axis show a deviation of the axis of rotation in the X-direction can be detected towards. In this case, status monitoring of the axis of rotation is possible, in particular when the pivot point is moving, since in this case a signal or phase difference would result. Monitoring of the position of the axis of rotation can thus be made possible.

In an advantageous development, the axial position of the at least two angle sensors, in particular at least two groups of angle sensors, can be different. As a result of an axially different positioning of the angle sensors or the groups of angle sensors, the amplitude of the useful magnetic field on each angle sensor is different. However, each angle sensor or each group of angle sensors would determine the same angle of the useful magnetic field. The influence of the interfering magnetic field is the same on all sensors, so that due to the gradient of the different axial Positioned angle sensors, the influence of the interference magnetic field can be determined. The influence can be determined purely arithmetically or by means of a characteristic curve or a map. The greater the axial distance between the angle sensors, the more a measurement angle would be influenced by the interfering magnetic field. For example, a correction factor can be determined as a function of a known useful field and various interference fields, and by a correction calculation, for example based on the angle value of the axially closest angle sensor to the magnetic field generating device and on the basis of a gradient of the two angles or the underlying sensor signals of the axially offset angle sensors by means of the Correction factor a correction to a true angle value can be determined. For this purpose, a characteristic curve for different strengths of useful and interference fields can be provided. A further, externally arranged magnetic field sensor can also be provided for detecting the size of the interfering magnetic field in order to use it to select a suitable correction value.

In a secondary aspect of the invention, a method for the interference field-compensated angle determination of an axis of rotation using an angle sensor device is proposed, in which an aforementioned embodiment of an angle sensor device is used, and in which an angle deviation between the at least two angle sensors of the angle sensor device can be used to compensate for an external interference field . The gradient, ie the angular deviation or a sensor signal deviation between the at least two angle sensors which are arranged axially and / or radially offset along the axis of rotation and which are exposed to the influence of a useful magnetic field of a magnetic field generating device, can be used to determine an external interference field and to be able to compensate. With an axial displacement of the angle sensors, a correction value would be able to be determined by a decrease in the amplitude of the useful magnetic field, however, with a practically identical influence of the interfering magnetic field. In the case of a radial offset, Due to different phases, but also different amplitudes and with the same influence of the interfering magnetic field, but different influence of the useful magnetic field, a correction can be made that offers a compensation option both in terms of hardware and calculation. In this way, the influence of an interference magnetic field can be effectively and easily compensated for, even with high interference magnetic fields, as prescribed by ISO-11452-8 from 2015, and exact angle values can be determined for interference fields with a field strength of up to 3 kA / m.

In an advantageous development of the method, a correction factor, a characteristic curve or a characteristic map of correction factors can be used to compensate for an external interference field. In particular in the case of an arithmetic post-treatment of the angle values of the individual angle sensors, a characteristic curve, a characteristic diagram or a correction factor can be used in order to compensate for the interfering magnetic field. Based on the above-mentioned method example, the correction factor, the characteristic curve or the characteristic field can be determined when the angle sensor device is manufactured with a calibration using various magnetic interference and useful fields. The correction factor or the correction factors or characteristic curves or characteristic diagrams can be stored in a memory of an angle calculation device and can be taken into account when determining the angle values of the various angle sensors.

In an advantageous development of the method, the correction factor can take into account an influence of an axial distance between the angle sensors and / or a radial distance between magnetoresistive resistance elements of the Wheatstone measuring bridge of the angle sensors. Thus, for example, several angle sensors, in particular four, eight or even more angle sensors, can be arranged at different axial and also radial distances along the axis of rotation, and their interference field compensation can partly be achieved by a hard-wired circuit of the resistance elements, possibly also with phase shifter elements, but also through arithmetic post-processing, for example through correction with correction factors. The correction factors can take into account an axial distance or a radial distance between the resistance elements. It is conceivable that radial and / or axial distances of the angle sensors can be changed in the course of the measurement or at intervals in order to thereby redefine the characteristics or characteristic values and to be able to recalibrate the angle sensor device.

DRAWINGS

Further advantages emerge from the present description of the drawings. Exemplary embodiments of the invention are shown in the drawings. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

Fig. 1

schematisch eine Winkelsensorvorrichtung aus dem Stand der Technik,

Fig. 2

eine Anordnung von Widerstandselementen und eine Widerstandsmessbrücke gemäß des Stands der Technik,

Fig. 3

radial um 90° versetzte Winkelsensoren,

Fig. 4

eine hart verschaltete Wheatstone-Messbrücke des in Fig. 3 dargestellten Bespiels,

Fig. 5

Quadropolmagnet und um 90° versetzte Winkelsensoren,

Fig. 6

ein Ausführungsbeispiel der Erfindung mit axial versetzten Winkelsensoren,

Fig. 7

ein weiteres Ausführungsbeispiel der Erfindung, das sowohl axial als auch radial versetzte Winkelsensoren kombiniert,

Fig. 8

ein weiteres Ausführungsbeispiel mit radial versetzten Widerstandselementen zweier Winkelsensoren,

Fig. 9

Anordnung von Widerstandselementen und Wheatstone-Messbrücke der in Fig. 8 dargestellten Ausführungsform,

Fig. 10

ein weiteres Ausführungsbeispiel von axial und radial versetzten Winkelsensoren,

Fig. 11

schematisch eine Winkelberechnungseinrichtung zum Verarbeiten der Winkelwerte verschiedener Winkelsensoren eines Ausführungsbeispiels.

Show it:

Fig. 1

schematically an angle sensor device from the prior art,

Fig. 2

an arrangement of resistance elements and a resistance measuring bridge according to the prior art,

Fig. 3

angle sensors offset radially by 90 °,

Fig. 4

a hard-wired Wheatstone measuring bridge of the in Fig. 3 example shown,

Fig. 5

Quadrupole magnet and angle sensors offset by 90 °,

Fig. 6

an embodiment of the invention with axially offset angle sensors,

Fig. 7

another embodiment of the invention, which combines both axially and radially offset angle sensors,

Fig. 8

another embodiment with radially offset resistance elements of two angle sensors,

Fig. 9

Arrangement of resistance elements and Wheatstone measuring bridge of the in Fig. 8 illustrated embodiment,

Fig. 10

another embodiment of axially and radially offset angle sensors,

Fig. 11

schematically an angle calculation device for processing the angle values of various angle sensors of an embodiment.

In the figures, similar elements are numbered with the same reference numerals. The figures show only examples and are not to be understood as restrictive.
In the Fig. 1 an embodiment 100 of an angle sensor device from the prior art is shown. The angle sensor device 100 has an axis of rotation 12, at the axial end of which a disk-shaped permanent magnet 10 is arranged as a dipole magnet with two dipole magnet circle segments as the north and south pole 18. The magnetic field generating device 16, which comprises the rotatable dipole magnet 10, is thus arranged at the axial end of the axis of rotation 12. The dipole magnet 10 has a diameter d _M and a height h _M. An angle sensor 20 of an angle sensor device 102 is arranged at an axial distance d _{as from the dipole magnet 10.} The dipole magnet 10 generates a U-shaped useful magnetic field aligned in the axial direction, which penetrates the angle sensor 20. in the Angle sensor 20 is a Wheatstone measuring bridge, as shown in Figure 2b is shown, integrated. The sensitive surface of the angle sensor 20 is oriented at right angles to the axis 12.

A plan view of the chip substrate surface of the angle sensor 20 is shown in FIG Fig. 2a the arrangement of the resistance elements for the sine bridge S1, S2 and the cosine bridge C1, C2 is shown. The resistance elements 24 can be AMR, GMR, TMR or, in general, xMR resistance elements. The angle sensor 20 comprises four resistance elements each for the sine branch and for the cosine branch, which can be contacted individually. The sinusoidal resistance elements S1, S2 are arranged opposite one another in pairs and are disposed axially centered around the axis of rotation 12 in a square offset by 90 ° in relation to the cosine resistance elements C1, C2.

In the Figure 2b shows a Wheatstone angle measuring bridge 22 with a phase-correct interconnection of the two Wheatstone measuring bridges for the sine and cosine parts. Each measuring bridge comprises four resistance elements 24, which are located diagonally opposite at the same point on the chip substrate surface. The angle of the useful magnetic field with respect to the chip substrate can be determined by forming the arctangent of the quotient of the sine and cosine values. If an external interfering magnetic field acts on the angle sensor device 100, this is superimposed on the useful field and leads to a falsification of the useful magnetic field angle, which becomes stronger the stronger the interfering magnetic field is in relation to the useful magnetic field. Significant angular distortions can occur, particularly with high interference magnetic fields of up to 3000 A / m, so that the angle of the axis of rotation cannot be determined exactly.

In the Fig. 3 a first embodiment 30 of an angle sensor device is shown. The angle sensor device 30 comprises a magnetic field generating unit 16 in the form of a dipole permanent magnet 10 with a north pole and a south pole 18. This is arranged in a rotationally fixed manner at the end of an axis of rotation 12. In an axial extension of the axis of rotation 12, an angle sensor device 50 is arranged, which also includes four angle sensors 20 that are radially evenly spaced about the axis of rotation. The angle sensors W11, W12, W13 and W14 each have a radius d _ss / 2 as a distance from the axis of rotation and are offset by 90 ° to one another. The sensitive plane of the individual angle sensors 20 is aligned parallel to the axis of rotation 12, so that magnetic fields that are aligned parallel to the axis of rotation can be detected. If an interference field acts from the outside, then all four angle sensors 20 of the angle sensor device 50 correspondingly deviate from an angle which is caused by the useful field of the magnetic field generating device 16. Since the useful field in each angle sensor 20 has a different phase due to the offset arrangement, but the interference has approximately the same effect in each of the sensors, the interference component can be filtered out due to the symmetrical arrangement of the sensors W11 to W14.

The Fig. 4 a Wheatstone bridge 70 in which the individual Wheatstone bridges of the four angle sensors 20 W11 to W14 are connected in parallel with the correct phase. To determine the sine component, for example, the sine bridge of the angle sensor W11, the negative cosine bridge of the angle sensor W12, the negative sine bridge of the angle sensor W13 and the cosine bridge of the angle sensor W14 are connected in parallel. These are thus connected in parallel with one another in the correct phase and a disturbance, which is reflected in all these bridges, can be compensated. In a similar way, the individual sine and cosine measuring bridges of the individual sensors 20 are connected in parallel for the cosine bridge. The cosine bridge of sensor W11 is connected in parallel to the sine bridge of sensor W12, the negative cosine bridge of sensor W13 and the negative sine bridge of sensor W14 in order to output an averaged cosine value. By connecting in parallel and hard wiring the individual bridges of the angle sensors 20, which are in phase with each other are combined, the disturbance of the interfering magnetic field can be compensated. The sine and cosine bridges of the four sensors 20 are thus wired to one another in the correct phase and carry out a signal message. The distance d _as between the angle sensor device 50 and the magnetic field generating device 16 can for example be between 1 mm and 3 mm, the diameter d _{m of} the permanent magnet being about 6 mm and the height h _{M of} the dipole magnet being about 2.5 mm. It is conceivable to use only two or more than four angle sensors in order to achieve improved averaging, the phases must be taken into account accordingly, or a subsequent averaging with the aid of delay transmitters must be inserted. The sensitive planes of the angle sensors can also be aligned at right angles to the axis of rotation 12. No electronic processing of the signals is required in order to suppress the interference fields, and at least a factor of 2 can be achieved in the suppression of the interference field.

In the Figs. 5a and 5b a further embodiment 32 of an angle sensor device is shown. The execution of the Figure 5a basically corresponds to the execution according to Fig. 3 However, a quadrupole magnet 14 is used as the magnetic field generating unit 16 which comprises four poles 18 which are alternately polarized. This makes it possible to detect a deviation of the axis of rotation in the X or Y direction, ie to detect a radial deviation, and thus to detect imbalances or a shifted axial profile of the axis of rotation 12. This is expressed by a phase difference in the angle detection of the individual sensors, although detection of up to 180 ° is only possible.
The Figure 5a shows schematically a perspective illustration of the angle sensor device 32, while Figure 5b represents a plan view. This enables the condition of the shaft 12 to be monitored, with the phase differences between the individual sensors changing, for example, when the pivot point is moving. The output signals of the individual sensors can be wired to one another in terms of hardware, for example in the Fig. 4 is shown. But they can also be prepared and processed individually, for example by a computer logic of an angle calculation device. The status of the rotor position can be monitored, since a slight change in the position of the axis of rotation results in a phase difference in the angle signals.

In the Figures 6a and 6b a further embodiment 34 of an angle sensor device according to the invention is shown. The angle sensor device 34 comprises a magnetic field generating device 16 with a disk-shaped dipole magnet 10 with two poles 18. The dipole magnet 10 is arranged at the axial end of an axis of rotation 12, has a diameter d _M and a height h _M. In the axial extension of the axis of rotation 12, a first angle measuring sensor 20 W1 is arranged at a distance d _as1 and a second angle sensor 20 W2 of the magnetic field _{generating device} 54 is arranged at a further distance d as2. Both angle sensors 20 detect the rotating useful field with different amplitudes. An interfering magnetic field acts uniformly on the two angle sensors W1 and W2 20, so that the angle of the two angle sensors will change in different directions, since the size of the useful field of the two angle sensors is different. This impact is in the Figure 6b shown, wherein an interference magnetic field B _ext acts in the plane of the angle sensors, the measuring active plane is oriented at right angles to the axis of rotation 12. The useful magnetic field B _{M is} angled to this. The measurement angle recorded by the axially closer angle sensor W1 is closer to the exact alignment of the useful magnetic field B _M , while the angle of the axially further away angle sensor 20 W2 is more strongly influenced by the external magnetic field B _ext . Since the two angle sensors 20 are arranged centrally above the axis of rotation at different axial distances, the magnetic field amplitude of the useful field decreases with the distance, while the interference field acts uniformly on both sensors. For example, in a typical permanent measuring magnet, a magnetic field generating device the distance d _{as1 is} 3 mm and the distance d _{as2 is} 1 mm or less. The distance d _as1 can be between 0.5 mm and 3 mm. The specified distances, which are intended to describe the distance relationships, can vary depending on the strength of the permanent measuring magnet used, although larger distances are of course possible. The greater the distance from the magnetic field generating device 16, the more strongly the field angle is influenced by the interference field. The gradient, that is to say the deviation of the sensor signals of the angle sensor 20 W1 from the angle sensor 20 W2, is stronger the greater the interference field. This deviation can be used to correct the measurement signal and the influence of the interference field can thereby be suppressed. The device can be used both with angle sensors in the narrower sense and with a combination of field sensors rotated by 90 ° to determine the field components in the X and Y directions.

For example, the axially closer angle sensor W1 detects the useful field with an angle ϕ1. The sensor W2 has a greater distance and detects an angle ϕ2. If there is no interfering magnetic field, ϕ1 = ϕ2 applies. If there is a homogeneous interfering magnetic field, there are two angular errors ϑ1 and ,2, where ϑ1 <ϑ2 applies. This results from the fact that the effective field acting on the two angle sensors W1 and W2 is of different strength. For an initial calibration or verification, ϑ1 and ϑ2 should be known, where ϑ1 must be determined in any case. A calibration or determination of a correction factor can take place in that with several sizes of useful fields and with several sizes of interference fields the angles ϕ1 and ϕ2 as well as werden1 are determined. From this, an angle difference δ = ϕ1-ϕ2 can be determined and a correction factor K = ϑ1 / δ = ϑ1 / (ϕ1-ϕ2) for all used fields and, in this case, known interference fields can be calculated. This results in a correction factor or a characteristic curve or a characteristic map of correction factors for different useful fields and different interference fields. During a measurement, the two angles ϕ1 and ϕ2 can be determined and then a correction of the true angle ϕ = ϕ1-K · (ϕ1- ϕ2) can be achieved become. It is also conceivable to provide an additional magnetic field or angle sensor which is arranged outside the angle sensor device and which detects the strength and direction of the interfering magnetic field in order to determine the correction factor K. In this way, an interference field can be effectively compensated.

In the Fig. 7 a further embodiment 36 of an angle sensor device is shown. This essentially corresponds to a combination of the in Figure 6a illustrated embodiment 34 and in Figure 5a illustrated embodiment 32. The angle sensors 20 of the angle sensor device 56 are both radially spaced and axially spaced and comprise in a first axially closer group W11 to W14 four angle sensors 20, which are each arranged radially offset by 90 ° about the axis of rotation 12, and which, for example hardwired can output a first angle ϕ1. Another group of angle sensors 20 W21 to W24 is located at an axial distance d _{as2 therefrom.} In this arrangement, interference fields can be suppressed both by the radial offset and a further influence of interference fields can be suppressed by the axial offset with the aid of a correction factor, so that an improved interference field compensation is made possible.

The Fig. 8 shows a further embodiment 38 of an angle sensor device. In this case, an angle sensor device 58, which comprises two angle sensors 20 W1 and W2, is arranged at an axial distance d _{as from the magnetic field generating device 16.} Both angle sensors 20 are arranged on a common chip substrate and each include a sine bridge and a cosine bridge made of magnetoresistive resistance elements. The resistance elements 24 of the first angle sensor 20 W1 and of the second angle sensor 20 W2 are arranged in a plane at right angles to the axis of rotation 12. The resistance elements 24 are each arranged along the edges of a square or a circle around the axis of rotation 12, the Resistance elements 24 of the first angle sensor 20 W1 are arranged axially closer to the axis of rotation 12 than the resistance elements 24 of the second angle sensor 20 W2. The arrangement of the individual resistance elements 24 is shown in FIG Figure 9a shown. _{The resistance elements} 24 C1 ', S1', S2 'and C2' of the first angle sensor 20 W1 are located at a close distance d ss1 to the axis of rotation 12, and the resistance elements 24 of the second angle sensor W2 S1, C1, C2 and S2 are located in one greater distance d _ss2 to the axis of rotation.

In the Figure 9b a Wheatstone bridge 72 is shown in which the individual resistance elements 24 of the two angle sensors 20 W1, W2 are interconnected so hard that the angle sensors 20 behave opposite to one another with respect to the useful magnetic field. The elements S1 and S2 'and the elements S1' and S2 are connected in series in one branch of the sine bridge and the elements S1 ', S2 and S1 and S2' are connected in the opposite branch. The arrangement is also chosen in the cosine bridge. This partially compensates for the useful signals of the two angle sensors, the basic principle being based on the fact that one angle sensor is penetrated by a stronger useful field than the other angle sensor. In this respect, the overall circuit 72 is the Figure 9b a damped sine and a damped cosine value. An interference field, which acts as it were on all resistance elements 24, would be completely compensated, since the respective rectified resistance elements 24 of the two angle sensors 20 W1, W2 almost completely compensate one another. Because of the different radial distances d _ss1 , d _{ss2 of} the resistance elements 24 of the measuring bridges 72 of the first angle sensor W1 to the second angle sensor 20 W2, the resistance elements 24 closer to the axis are penetrated more strongly by the useful field than the resistance elements 24 further away from the axis, an angle value can be determined . As a rule, the useful field acts more strongly on the radially inner resistance elements 24 of the angle sensor W1 than on the radially outer resistance elements 24 of the angle sensor W2, so that the dominant portion of the useful angle signal is generated by the angle sensor W1. The angle sensor W2 compensates for this useful signal to a lesser extent and virtually completely compensates for an external interference signal. As in Figure 9b is shown, the circuit can be wired in terms of hardware, so that a total angle value can be output, and no numerical recalculation is necessary. This exemplary embodiment is particularly suitable for use in GMR or TMR resistance elements 24, since these can be pinned in a direction-dependent manner and thus enable 360 ° detection and have a high level of sensitivity.

In the Fig. 10 a further embodiment 40 is shown, which basically consists of a combination of the in Fig. 8 embodiment shown and in Figure 6a illustrated embodiment results. Thus, a radial offset of the resistance elements 24 of two groups of two angle sensors W11, W12 and W21, W22 is used, as well as the gradient _{utilization of different axial distances of the distances d as1} and d _{as2 of} the two groups W11, W12 and W21, W22 and the Taking a correction factor into account, further interference field suppression is possible. In particular, three-dimensional interference fields which act on the angle detection unit 60 both in the axial and in the radial direction can be effectively suppressed as a result.

Finally shows Fig. 11 an embodiment of an angle sensor device in which angle values of individual angle sensors 20 of an angle sensor device 50, 52, 54, 56, 58 or 60 according to the embodiments 30, 32, 34, 36, 38 or 40 are recorded individually. The angle calculation device 26 comprises a characteristic value memory 44, which includes various characteristic values K for different useful field sizes and interference field sizes, as well as a calculation unit 46 which calculates an interference field-compensated angle ϕ as a function of two or more measured angles in the angle sensor device 50, 52, 54, 56, 58 or 60 included angle sensors 20 are detected. The angle sensors 20 or groups of angle sensors 20 are arranged at different axial distances from the magnetic field generating device 16, a characteristic map K, which can be read from the characteristic value memory 44, being used to correct the interference field influence. Finally, an interference field-compensated angle value ϕ66 is output.

The invention proposes several embodiments of angle sensor devices 30, 32, 34, 36, 38 or 40, in which two or more angle sensors 20 are used in an angle sensor device 50, 52, 54, 56, 58 or 60, both axially and radially are arranged offset about an axis of rotation 12 in the vicinity of a magnetic field generating device 16. On the basis of a gradient of the angle measurement, ie different angle measurements of the individual angle sensors 20, an influence of an interference field can be determined and compensated. The geometric relationships as well as compensation effects due to different spatial arrangements can be used. The interference field compensation can on the one hand be permanently wired on the hardware side, on the other hand it can be carried out subsequently by means of a calculation unit. With the help of an angle sensor device 30, 32, 34, 36, 38 or 40 according to the invention, interference fields can also be effectively compensated in the range of up to 3,000 A / m field strength, so that the new ISO-11452-8: 2015 can be complied with.

List of reference symbols

10

Permanent magnet, dipole magnet

12th

Axis of rotation

14th

Permanent magnet, quadrupole magnet

16

Magnetic field generating device

18th

Magnetic pole

20th

Angle sensor

22nd

Wheatstone measuring bridge of an angle sensor

24

magnetoresistive resistance element

26th

Angle calculator

30th

First embodiment of an angle sensor device

32

Second embodiment of an angle sensor device

34

Third embodiment of an angle sensor device

36

Fourth embodiment of an angle sensor device

38

Fifth embodiment of an angle sensor device

40

Sixth embodiment of an angle sensor device

44

Characteristic value memory

46

Calculation unit

50

Angle sensor device of the first embodiment

52

Angle sensor device of the second embodiment

54

Angle sensor device of the third embodiment

56

Angle sensor device of the fourth embodiment

58

Angle sensor device of the fifth embodiment

60

Angle sensor device of the sixth embodiment

64

Sensor signals or angle value from an angle sensor

66

Interference field compensated angle value

70

Wheatstone bridge of the angle sensor of the first embodiment

72

Wheatstone bridge of the angle sensor of the fifth embodiment

100

Angle sensor device from the prior art

102

Prior art angle sensor device

Claims (14)

1. Interference field-compensated angle sensor device (30, 32, 34, 36, 38, 40) for magnetic field-based determination of a rotation angle of a rotation axis (12) comprising a magnetic field generating unit, in particular a permanent magnet (10, 14), and an angle sensor unit (50, 52, 54, 56, 58, 60), with a magnetic field of the magnetic field generating unit (16) rotating relative to the angle sensor unit (50, 52, 54, 56, 58, 60), and the angle sensor unit (50, 52, 54, 56, 58, 60) comprising at least two angle sensors (20) for sensing different magnetic field areas of the magnetic field of the magnetic field generating unit, characterized in that the angle sensors (20) are arranged axially offset at different distances along the rotation axis (12) and/or the angle sensors (20) are arranged radially offset at different distances to the rotation axis (12) for sensing different amplitudes of the magnetic field, such that an influence of an interference field is compensatable by a gradient formation of the angle values or sensor signals (64) of the angle sensors (20).
2. Angle sensor device (30, 32, 34, 36, 38, 40) according to claim 1, characterized in that the magnetic field generating unit (16) is designed as a permanent magnet (10, 14), in particular as a dipole magnet (10), which is arranged non-rotatably on an end face of the rotation axis (12), and the angle sensor unit (50, 52, 54, 56, 58, 60) is arranged in an axial extension of the rotation axis (12) opposite the end face of the rotation axis (12).
3. Angle sensor device (30, 32, 34, 36, 38, 40) according to one of the aforementioned claims, characterized in that the angle sensors are xMR angle sensors (20), in particular AMR, TMR or GMR sensors.
4. Angle sensor device (30, 32, 34, 36, 38, 40) according to one of the aforementioned claims, characterized in that each angle sensor (20) comprises a Wheatstone bridge (22, 70, 72) of magnetoresistive resistor elements (24), the Wheatstone bridges (22, 70, 72) of the different angle sensors (20) being hardwired to one another and outputting an interference field-compensated angle sensor value (66).
5. Angle sensor device (30, 32, 34, 36, 38, 40) according to one of the aforementioned claims 1 to 3, characterized in that an angle computation unit (26) is comprised that receives angle values (64) or sensor signals of each angle sensor (20) of the angle sensor unit (50, 52, 54, 56, 58, 60) and processes them to calculate an interference field-compensated angle value (66).
6. Angle sensor device (30, 32, 34, 36, 38, 40) according to one of the aforementioned claims, characterized in that the angle sensors (20) of the angle sensor unit (50, 52, 54, 56, 58, 60) are arranged axis-centric.
7. Angle sensor device (30, 32, 34, 36, 38, 40) according to claim 6, characterized in that each angle sensor (20) comprises a Wheatstone bridge (22, 70, 72) of magnetoresistive resistor elements (24), the respective radial distances between the magnetoresistive resistor elements (24) of the Wheatstone bridge (22, 70, 72) of each angle sensor (20) from the rotation axis (12) differing.
8. Angle sensor device (30, 32, 34, 36, 38, 40) according to claim 7, characterized in that die radially offset magnetoresistive resistor elements (24) of the angle sensors (20) are connected in opposite directions to form a self-compensating Wheatstone bridge (22, 70, 72).
9. Angle sensor device (30, 32, 34, 36, 38, 40) according to claim 8, characterized in that the magnetic field generating unit (16) comprises a permanent magnet (10, 14) with the same number of poles as angle sensors (20), in particular a quadrupole magnet (14).
10. Angle sensor device (30, 32, 34, 36, 38, 40) according to one of the aforementioned claims, characterized in that the axial positions of two groups of angle sensors (20) differ.
11. Method for interference field-compensated angle determination of a rotation axis (12) using an angle sensor device (30, 32, 34, 36, 38, 40) according to one of the aforementioned claims, characterized in that an angle divergence between the angle sensors (20) of the angle sensor unit (50, 52, 54, 56, 58, 60) is used for compensation of an external interference field.
12. Method according to claim 11, characterized in that a correction factor or a characteristic curve or a characteristic field of correction factors is used for compensation of an external interference field.
13. Method according to claim 12, characterized in that the correction factor or the characteristic curve or the characteristic field is determined during manufacture of the angle sensor device (30, 32, 34, 36, 38, 40) in a calibration step using various magnetic interference fields and useful fields.
14. Method according to one of claims 12 or 13, characterized in that the correction factor takes into account an influence of an axial distance of the angle sensors (20) and / or a radial distance of magnetoresistive resistor elements (24) of the Wheatstone bridge (22, 70, 72) of the angle sensors (20).

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